In the year 2258, it is ten years after the Earth-Minbari War. Commander Sinclair takes command of a giant five-mile-long cylindrical space station, orbiting a planet in neutral space. At a crossroads of interstellar commerce and diplomacy, Cmdr Sinclair (2d season Captain Sheridan) must try to establish peace and prosperity between various interstellar empires, all the while fighting forces from within the Earth Alliance. It is a precarious command, particularly given that sabotage led to the destruction of Babylon stations 1, 2, and 3 and 4 vanished without trace.

[Opening narration, season 1] Commander Jeffrey David Sinclair: It was the dawn of the third age of mankind, ten years after the Earth-Minbari War. The Babylon Project was a dream given form. Its goal: to prevent another war by creating a place where humans and aliens could work out their differences peacefully. It's a port of call, home away from home for diplomats, hustlers, entrepreneurs, and wanderers. Humans and aliens wrapped in two million, five hundred thousand tons of spinning metal, all alone in the night. It can be a dangerous place, but it's our last, best hope for peace. This is the story of the last of the Babylon stations. The year is 2258. The name of the place is Babylon 5.

[Opening narration, season 2] Captain John Sheridan: The Babylon Project was our last, best hope for peace, a self-contained world five miles long located in neutral territory, a place of commerce and diplomacy for a quarter of a million humans and aliens, a shining beacon in space, all alone in the night. It was the dawn of the third age of mankind, the year the great war came upon us all. This is the story of the last of the Babylon stations. The year is 2259. The name of the place is Babylon 5.

[Opening narration, season 3] Susan Ivanova: The Babylon Project was our last, best hope for peace. It failed. But in the year of the Shadow War, it became something greater: our last, best hope for victory. The year is 2260. The place - Babylon 5.

[Opening narration, season 4] Lennier: It was the year of fire, Zack Allan: The year of destruction, Citizen G'Kar: The year we took back what was ours. Lyta Alexander: It was the year of rebirth, Ambassador Vir Cotto: The year of great sadness, Marcus Cole: The year of pain, Delenn: And a year of joy. Ambassador Londo Mollari: It was a new age. Dr. Stephen Franklin: It was the end of history. Susan Ivanova: It was the year everything changed. Michael Garibaldi: The year is 2261. Captain John Sheridan: The place, Babylon 5.

Delenn: I am Grey. I stand between the candle and the star. We are Grey. We stand between the darkness and the light.

Movie Trivia:

Claudia Christian auditioned for the role of Seven of Nine on "Star Trek: Voyager" (1995). In fact, several B5 actors also did Trek: Andreas Katsulas was Romulan Commander Tomalak; Bill Mumy was an engineer on Starfleet's AR-558 outpost; and more. Trek co-creator Majel Barrett made an appearance on B5 as the seer who foretells Londo's ascension to the throne. Majel Barrett's character, Lady Morella, was the widow of the recently deceased Emperor Turhan, no doubt an homage to Gene Roddenberry.

When B5 entered production, there were claims that the creators of "Star Trek: Deep Space Nine" (1993) had stolen the basic Babylon 5 premise. It was never proven, though both shows share striking similarities. This controversy led to friction between Babylon 5 and Star Trek fans over the course of both series.

The Babylon 5 station is an "O'Neil class space station". Gerard K. O'Neill was a physicist and space visionary who suggested the use of large rotating cylindrical habitats for future space stations.

The Medlab was deliberately designed to display few tools and instruments. The designers considered less to be more in guessing future medical technology.

The Babylon 5 station is claimed to be operated by an artificial intelligence computer system provided by the Centauri.